1. Field of the Invention
The embodiments discussed herein relate to a treatment liquid application device, and an image forming system including the treatment liquid application device.
2. Description of the Related Art
Inkjet image formation has rapidly become popular owing to its advantages of easy colorization as well as low noise, and low running cost. There are two types of inkjet printers employing such an inkjet system, namely, a serial printer and a line printer. The serial printer is configured to print images by combining an operation to eject ink droplets while moving a recording head in a main-scanning direction (i.e., a recording medium width direction) and an operation to move a target recording medium in a sub-scanning direction. The line printer including a line head having a printing width that equates with a width of the target recording medium, and is configured to print images by relatively moving the line head and the target recording medium.
FIG. 12 is a schematic diagram illustrating a flow of an inkjet image forming system according to an embodiment of the present invention. As illustrated in FIG. 12, a treatment liquid application device 220 is configured to apply a treatment liquid having a function to flocculate ink to a recording medium W before ink droplets drip onto the web (i.e., recording medium) W in order to prevent an image formed on the recording medium W from bleeding, exhibiting degraded density or degraded color tone, or exhibiting strike-through. The treatment liquid application device 220 is configured to apply the treatment liquid on a surface and/or a rear surface of the recording medium W. The treatment liquid application device 220 is employed by the system illustrated in FIG. 12.
A print system 200 includes a sheet feeding device 210, the treatment liquid application device 220, a first inkjet printer 230, an inverting device 240, a second inkjet printer 250, a post-drier device 260, and a rewinder 270. The sheet feeding device 210 is configured to feed the roll sheet recording medium W formed of a long continuous paper or the like to the treatment liquid application device 220 disposed downstream in a recording medium W transfer path.
The treatment liquid application device 220 is configured to apply the treatment liquid to the recording medium W for prevent ink bleeding or ink strike-through appearing on the recording medium W, and to dry the recording medium W to which the treatment liquid has been applied.
FIG. 14 is a schematic configuration diagram illustrating a related art treatment liquid application device previously considered by the inventors of the present invention viewed from a front side, and FIG. 15 is a schematic configuration diagram illustrating the related art treatment liquid application device viewed from a lateral side.
The related art treatment liquid application device includes, as illustrated in FIG. 14, an application roller 1 having a periphery covered with an elastic member such as rubber, a squeeze roller 2 disposed below the application roller 1, and a pressure roller 3 disposed above the application roller 1. The application roller 1, the squeeze roller 2, and the pressure roller 3 are, as illustrated in FIG. 15, disposed in approximately a vertical direction.
The application roller 1 and the squeeze roller 2 are each rotationally driven independently by a not-illustrated driving source such as a motor. As illustrated in FIG. 14, two ends of the application roller 1 are rotationally supported (fixed) on a frame 32 via respective bearings 16.
Further, as illustrated in FIG. 14, squeeze retaining rollers 4 are disposed underneath the squeeze roller 2 along a longitudinal direction of the squeeze roller 2 at approximately regular intervals. The squeeze retaining rollers 4 are rotationally supported inside respective retaining roller holders 8. Respective stick-like holder supporting members 30 are connected to lower parts of the retaining roller holders 8, and washers 31 are disposed one on each middle position and each lower end of a corresponding one of the holder supporting members 30. A slightly compressed coil-like pushup spring 5 is disposed between the washer 31 disposed on the middle position and the washer 31 disposed on the lower end of the holder supporting member 30.
Lower parts of the pushup springs 5 are supported by respective arms 7. A point A of each of the arms 7 serves as a swing center. Each of the arms 7 includes a free end on a side opposite to the point A of the arm 7, and respective squeeze cams 6 are disposed on the free ends of the arms 7. Hence, the free ends of the arms 7 are constantly in contact with the respective squeeze cams 6 by elasticity of the pushup springs 5.
Each arm 7 swings based on the point A serving as a fulcrum point by rotations of the squeeze cam 6, and the swing of the arm 7 compresses the pushup spring 5. The spring load of the pushup spring 5 is transmitted to the corresponding squeeze roller 2 via the holder supporting member 30, the retaining roller holder 8, and the squeeze retaining roller 4. The spring load transmitted to the squeeze roller 2 pushes up the squeeze roller 2 in the application roller 1 direction to finally form a nip part between the squeeze roller 2 and the application roller 1. Note that the rotational angle of the squeeze cam 6 is controlled based on detected signals of a not illustrated rotating position detector such as an encoder.
As illustrated in FIG. 14, the application roller 1 and the squeeze roller 2 are housed inside a supply pan 9. A treatment liquid L is supplied from a tank 10 into the supply pan 9 by a pump 11, such that a part of the squeeze roller 2 is soaked in the treatment liquid L. A liquid level of the treatment liquid L inside the supply pan 9 is monitored by a liquid level detecting sensor 12, and the liquid level inside the tank 10 is retained at a predetermined level by controlling the drive of the pump 11 based on detected signals from the liquid level detecting sensor 12.
The two ends of the pressure roller 3 is rotationally supported on a free end side of the arm 22 that swings based on a D point as the center (see FIG. 15), and the arm 22 is pulled by an extension spring 23 in a counterclockwise direction based on the D point as the center. Further, a cam 25 is disposed on the extension spring 23 side of the arm 22, and the cam 25 is attached to a shaft 24 (see FIG. 14).
Not-illustrated driving source and rotation angle detector are connected to the shaft 24. Hence, a swing angle of the arm 22 is determined by the rotation angle of the shaft 24 (the cam 25), such that the position of the pressure roller 3 with respect to the application roller 1 may be changeable as a result. A web W is inserted between the application roller 1 and the pressure roller 3. When the web W starts being transported by a not-illustrated web transporting mechanism and the speed of the transporting operation reaches a predetermined speed, the pressure roller 3 makes a pressure-contact with the application roller 1 by the arm 22 and the cam 25.
Note that FIGS. 14 and 15 illustrate a standby state before the treatment liquid application device applies a treatment liquid L to the web W. In this state, the application roller 1 and the squeeze roller 2 are not rotated, and the web W is not transported.
The treatment liquid application device is configured to measure the amount of the treatment liquid L when the treatment liquid L is supplied to the nip part between the squeeze roller 2 and the application roller 1. The treatment liquid L passes through the nip part to form a thin treatment liquid layer on a surface of the application roller 1. The thickness (amount) of the treatment liquid layer may be adjusted by load applied by the pushup spring 5. The treatment liquid L is transferred onto the web W by causing the pressure roller 3 to press the web W against the application roller 1, on the surface of which the thin treatment liquid layer is formed.
Note that Japanese Laid-open Patent Publication No. 2010-158602 (Patent Document 1) and Japanese Laid-open Patent Publication No. 2008-260307 (Patent Document 2) may be given as related art technologies associated with the treatment liquid application device.